Separation is an industrial process which is often used in the food industry. Fat separation by such a process is used, for example, for milk and whey. The separation normally takes place in a centrifugal separator.
In its interior, the separator has a number of conical inserts disposed in a stack with a well-defined spacing between the inserts. The inserts are provided with distribution holes which are vertically disposed. Through these holes, the milk or whey arrives from the inlet into the separation section proper and is subjected to centrifugal force. Particles and impurities in the milk or the whey move outwards along the surfaces of the inserts and are accumulated in a sediment tank. The lighter phase of the liquid food, i.e. the fat/the cream, moves inwards along the surfaces of the inserts towards the rotation shaft and is conveyed out from the separator through an axial outlet. The heavier phase, which may consist of skimmed milk or whey which has been freed of fat globules, moves outwards along the surfaces of the inserts and is accumulated to an outlet. Modern separators may have different constructive concepts. The present invention may be employed for all types of centrifugal separators.
One common area of use for the separation process is the separation of milk, where the milk is separated into a skimmed milk phase and a cream phase. Thereafter, the milk may be standardised, for example to consumer milk possessing the desired fat content, in that a part of the cream phase is recycled back to the skimmed milk phase.
The separation process is also employed to extract fat from whey. Whey is a by-product in cheesemaking and, since roughly a third of the world's milk production is used for cheesemaking, this implies that almost a third of all milk becomes whey. Whey, which had previously only been employed as animal feed and as fertilizer, risked becoming an environmental problem. Today, whey has more or less come to be considered as a valuable raw material in the production of protein with a high nutrient value. The fat which is extracted from the whey is normally recycled to the cheesemaking process or to other parts of the dairy process.
It is an attractive option to increase the fat separation in all separation processes, above all in the separation of whey. By separating off more fat from the whey, a more efficient and more economical process can be obtained in a later production of protein.
Earlier attempts to increase the yield in the light phase, i.e. to extract more fat from the milk or whey have involved the use of larger separators. Larger separators imply larger capital costs, both as investment costs and as operational costs.
Swedish Patent Specification SE 526828 describes a method for improving the efficiency of the fat separation in whey separation. The whey is separated in a first separator or alternatively several separators. The light phase from this or these separators is thereafter separated in a second separator. In order to obtain a good level of capacity for this method, at least two first separators are required, whereafter an additional separator is also required.